The Airco DH4 was a two-seat bomber with a clean, tractor layout and a non-rotary engine that improved handling and stability as the torque produced by in-line engines was nowhere near that of a rotary engine. It was the first bomber designed specifically for day light bombing. It first served in 1917 and was withdrawn from service in 1932.

Technical Details
The DH4 was powered by a Rolls-Royce Eagle 3 V12, water-cooled engine producing 375 hp. Many other engines were also substituted for the R-R, each affecting power and performance. With the Rolls-Royce engine the DH4 was a maximum speed of 136 mph, a climb rate of 1,042 ft/min and ceiling of 20,000 ft. It had an operational range of 420 miles. With the RFC the DH4 was armed with a single, forward firing 0.303 Vickers machine gun and either one or two 0.303 Lewis machine guns on a ring for the observer/gunner. The RNAS had the machine armed with twin forward firing Vickers machine guns as well as the rear Lewis gun. It was capable of carrying 460 lbs of bombs.

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Image From: Taylor and Bowyer, Pictorial History of the RAF, Vol. 1 1918-1939